Large-Eddy Simulation #181: TIBL (with restoring zones)
LES RUN #181: TIBL.
We found that unrealistic east-west pressure-gradients were developing in
our previous TIBL simulations with open boundary conditions. To correct for this
in #181 we switched to periodic in both lateral directions and installed
large "restoring zones" (900 m wide) in the east-west ends of the domain.
This simulation is 800x120x69 grid-points with 15-m resolution in
all directions and 0.5 s time-step was used. The western 6-km is
over snow-covered land and the eastern 6-km over 279-K water.
Click here to see the NMSTASK file .
The following image and animation is a horizontal slice of model output near the surface
from the second half-hour of simulation. We are only showing the right
half of the model domain (the part over water). To make the picture and animation,
we have repeated the image once
in the north-south direction to allow your eye to more easily track
coherent structures across
the domain and for a more direct comparison with the
lidar PPI scans.
This numerical advection scheme used in this simulation is Sadourney (19??).
It is used with the intention of preserving enstrophy, KE and vorticity, and
therefore eliminate the non-physical downscale cascade of energy.
The model
relative humidity and passive tracer output has been used in a function
to mimic the
effects of aerosol swelling and increased lidar backscattering.
The following is a vertical east-west slice of model output for comparison
with the
lidar RHI-scans.
Here is an image of the pressure-perturbation fields of
LES #149 (open E-W BCs) and #181 (periodic in lateral directions)
for comparison.
Here is an image and an animation of the pressure-perturbation field on an
east-west oriented vertical slice.
Here is an image and an animation of the model relative-humidity field on a horizontal slice near the surface.
Here is an image and an animation of the model relative-humidity field on a east-west vertical slice.
UW Lidar // Mar 16, 2000 // root@lidar.ssec.wisc.edu
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